It sounds like he does have a very negative teacher and I don't see how belittling students could be helpful. However, from the perspective of a teacher and a parent of an HG+ student, I would not necessarily discount her recommendation. You said your DS has made two B's and a C this year and is accelerated. To me, it sounds like he may be in the right place. Honors is generally not just for students who can conceptualize advanced math but also for students who pay close attention to detail and produce excellent work. Sometimes that takes superior EF skills and often these skills mature with age, your DS just may not be there yet. Potential is not performance and having experienced this issue from both sides I have found that discounting what the teacher says is not always the best idea. There tends to be a grain of truth in everyone's perspective. Good luck with your choice and sorry that your DS has been subjected to such a negative teacher.